How To Fix ‘RPC Server is Unavailable’ Error in Windows

If you use Windows often, you’re probably familiar with one of the most commonly seen and seemingly inexplicable error messages to ever appear: “RPC Server is Unavailable.” Although this error can cause great confusion to inexperienced Windows users, it isn’t a serious or dangerous error, meaning it won’t usually cause you to lose any data or programs. It’s also, thankfully, pretty easy to fix if you know what you’re doing.

Although we are going to talk about RPCs in Windows systems in this article, you should be aware that the RPC methodology is used on just about every kind of computer system in use today. It’s a methodology, not a Windows-specific process. Most RPC server errors occur within one computer, but the cause of the problem can be something on that computer or something in the network as a whole. I’ll show you how to figure out both kinds of problems in this article.

What is RPC?

First, let’s talk about what RPC is in the first place to relieve some of the confusion and mystery. RPC stands for “remote procedure call”, and it is a method that computers have used literally for decades to communicate with one another. What makes things a little confusing is that with modern PCs multitasking and running many programs at once, RPC has become a method that some applications use to communicate with other applications running on the same computer.

RPC is basically just a system that allows different processes to communicate with each other to perform a task. It works a bit like networking in that the RPS server will open a port, communicate with the destination service or server, await a response, send a packet when it has a response, and then transfer the task data to the destination server or service. The whole process operates in reverse when the destination service or server has done its job and has data to send back to the initiating program.

RPC ‘Server is unavailable’ Errors

So what would cause an “RPC server unavailable” error? Well, let’s say that one service on your computer needs to communicate with another, so it contacts the RPC server on the computer to initiate the exchange. The RPC server uses ports on your computer to “listen” and “talk”, and it is the server that does the actual enabling communication between services, whether they are networked or local. If the call to the RPC server fails because the server is unavailable, does not respond, cannot write to memory, or cannot open a port, then the “RPC server is unavailable” error is triggered.

How to Fix ‘RPC server is unavailable’ Errors

On a Windows 10 machine, there are three basic potential causes for this error message. Either the RPC service is not running, there are issues with the network, or some important registry entries that control the RPC service have been corrupted. In Windows 10, the most common cause for the error is that the RPC service is simply not running.

The first thing to try with any Windows error is a full reboot. If the RPC service stopped working owing to a temporary issue, then a reboot will restart it along with the rest of the computer, so this is the first thing to try. If a reboot doesn’t resolve the error, then try the following fixes. Note that these fixes are written specifically for Windows 10 computers, but the same general processes can be used on previous versions of Windows.

RPC Service

If a reboot doesn’t solve the problem, then the first thing to check is to see whether the RPC service is actually running.

1. Right click on the Windows Task Bar and select Task Manager, you can also use the Ctrl + Shift + Esc hotkey.
2. Select the Services tab.
3. Then, click on the Open Services link near the bottom-left of the window.
4. Navigate to the Remote Procedure Call service. Ensure it is running and set to Automatic.
5. Navigate to the DCOM Server Process Launcher. Ensure it is also running and set to Automatic.

If the two services are set to anything other than Automatic and Running, change them. Depending on your system permissions, you can also restart these services. If you have rebooted your computer already this won’t achieve anything as they will already have been restarted.

Network Issues Causing RPC Server Errors

Even if a particular RPC call might be operating completely internally on your computer, it still uses the network stack to communicate. That means that issues with TCP or your firewall can stop RPC from working.

1. Type ‘control’ into the Windows Search box and select Control Panel.
2. Next, select Network and Internet.
3. Then, click on Network and Sharing Center.
4. Select the Ethernet link in the center and then Properties in the popup box.
5. For most home networks, you’ll want to ensure IPv4 and File and Printer Sharing for Microsoft Networks are both enabled.

If both IPv4 and File and Printer Sharing for Microsoft Networks already are checked, you’ll need to check the firewall.

1. If you use Windows Defender Firewall, select it in the Network and Sharing Center settings page, it’s in the bottom-left corner.
2. Find Remote Assistance and make sure it is enabled for Domain, Private and Public networks.
3. Save any changes if you made them.

If you use a third-party firewall, you may have to experiment to enable this setting. You shouldn’t need to change anything if you have been using your firewall for a while but check just in case.

Flush Your DNS Server

As mentioned by Jeff in the comments, if your services are running and you’re still having issues with this error, then perform a DNS flush.

1. Open the Start menu, type “command prompt” and click on Command Prompt, you can also use Windows PowerShell. Note, you might need to select Run as administrator. 
2. Now, type “ipconfig /flushdns“, without the quotes, and hit Enter.

Your DNS server has now flushed it’s files, hopefully that resolved your issue.

Registry Errors Causing RPC Server Errors

OK, so rebooting didn’t help, your RPC and DCOM services are running fine, and the network stack is chugging along. (You probably wouldn’t be reading this article if it wasn’t, anyway.) The last thing you can do is to check the registry entries that control the RPC and DCOM services to make sure they haven’t been corrupted. Messing around with the registry isn’t for the faint of heart but if you make a backup of it first, you can always undo anything you change. So let’s back the registry up first.

1. Type “regedit” into the search box and hit Enter.
2. Select Computer from the left side.
3. Go to File>Export.
4. At the Export Registry File dialog, type a name for the backup file and hit Save.

Now that you have a safe copy of your registry stowed away, you can check the entries for the RPC and DCOM services.

1. Navigate to HKEY_LOCAL_MACHINESYSTEMCurrentControlSetservicesRpcSs.
2. Select the Start key in the right pane and make sure the value is set to (2).
3. Navigate to HKEY_LOCAL_MACHINESYSTEMCurrentControlSetservicesDcomLaunch.
4. Select the Start key in the right pane and make sure the value is set to (2).
5. Navigate to HKEY_LOCAL_MACHINESYSTEMCurrentControlSetservicesRpcEptMapper.
6. Select the Start key in the right pane and make sure the value is set to (2).

If you have tried all these fixes and RPC server errors still appear, it’s time to restore from a restore point or refresh Windows. Just make sure to select the options that don’t overwrite your files and settings if you go for the refresh!

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Need to clean out your registry? Check out our article about the best registry cleaners for Windows 10. Need to stop your kids or coworkers from getting into your registry settings? We have you covered with our tutorial on locking down access to the registry editor. And if you need to speed up your machine, see our article on using the registry to make your Windows 10 PC faster.